Patent application WO00/37269 describes a flexible, non-pneumatic tyre in which the load is borne by laminated parts comprising a stack of composite layers essentially consisting of fibres embedded in a resin with interposed layers of rubber, the overall assembly making it possible to obtain a very strong structure capable of withstanding major deformation without suffering damage. In the present application, the term “composite” is reserved to elements based on fibres and a matrix in which said fibres are embedded; on the basis of this definition, the interleaved rubber layers present in said laminated parts are not part of the composite.
Furthermore, if it is desired to provide said elastic tyre, like any other industrial product, with the best opportunities for commercial success, it is also essential to be able to produce said industrial product by a robust, non-deviating process, i.e. a process with which the properties of the resultant product may readily be controlled. Furthermore, for parts which are to be produced in very large numbers, it is most desirable for the process to be suitable for elevated manufacturing rates.
Application EP-A-1 074 369 has proposed a process for manufacturing composite parts, one of the secondary objects of said process being to make it possible to combine the composite part with rubber in order to produce a laminated element suitable for use in resilient solid tyre. The present application describes a process comprising a prepolymerisation phase: fibres are embedded in a matrix based on a composition comprising a thermosetting resin, the composition containing said fibres is exposed to ionising radiation in order partially to polymerise the resin and obtain a precomposite (also designated “pregelled” composite) in which said composition is in the solid phase. The desired result is to obtain a finished part without appreciable degradation of the maximum possible reinforcing action depending on the fibres selected, it being possible for the part to have very different shapes, in particular very small radii of curvature. The load-bearing parts described in application WO00/37269 may be manufactured in accordance with the process described in said application EP-A-1 074 369.
With regard to bonding to rubber, said application EP-A-1 074 369 mentions the use of a well-known adhesive of the resorcinol-formaldehyde latex type (known as “RFL”), which is dried before receiving said rubber layer in the uncured state. In this manner, a certain degree of connection is obtained between the precomposite and the rubber. Then, the final moulding step of the laminated part, with heat treatment under pressure, makes it possible not only to crosslink or cure the rubber, but also to achieve complete polymerisation of the resin and an excellent connection between the composite and the rubber.
Unfortunately, however, the use of an unpolymerised RFL adhesive, while making it possible to dispense with using special elastomers to stick the rubber to the composite material and enabling the production of a mechanically effective bond, does entail an additional, intermediate drying step of said RFL adhesive prior to contact with the rubber, which is somewhat inimical to achieving elevated production rates.